Married as of January, with mostly separate finances slowly growing more integrated. Wouldn't be surprised to see us end up with mostly integrated finances given a bit of time, especially if we have a child (we don't have one now). We were 37 (me) and 35 (her) when we married, so we had a lot of time to get used to managing our own finances.
Based on my experience so far, it's much easier to reduce costs and accumulate wealth as a couple for any given level of consumption. The flip side is that the person with the most frugal preferences (if there is a difference) is generally going to face a certain amount of lifestyle inflation. In my case, that means living in a more expensive city. I don't dislike living here, but I could be happy in a smaller town if my wife could be too.
And then there's the question of children....